Pharmaceuticals as environmental contaminants have received a lot of interest over the past decade but, for several pharmaceuticals, relatively little is known about their occurrence in European surface waters. Benzodiazepines, a class of pharmaceuticals with anxiolytic properties, have received interest due to their behavioral modifying effect on exposed biota. In this study, our results show the presence of one or more benzodiazepine(s) in 86% of the analyzed surface water samples (n = 138) from 30 rivers, representing seven larger European catchments. Of the 13 benzodiazepines included in the study, we detected 9, which together showed median and mean concentrations (of the results above limit of quantification) of 5.4 and 9.6 ng L, respectively. Four benzodiazepines (oxazepam, temazepam, clobazam, and bromazepam) were the most commonly detected. In particular, oxazepam had the highest frequency of detection (85%) and a maximum concentration of 61 ng L. Temazepam and clobazam were found in 26% (maximum concentration of 39 ng L) and 14% (maximum concentration of 11 ng L) of the samples analyzed, respectively. Finally, bromazepam was found only in Germany and in 16 out of total 138 samples (12%), with a maximum concentration of 320 ng L. This study clearly shows that benzodiazepines are common micro-contaminants of the largest European river systems at ng L levels. Although these concentrations are more than a magnitude lower than those reported to have effective effects on exposed biota, environmental effects cannot be excluded considering the possibility of additive and sub-lethal effects.
Contact CEH NORA team at noraceh@ceh.ac.ukThe NERC and CEH trademarks and logos ('the Trademarks') are registered trademarks of NERC in the UK and other countries, and may not be used without the prior written consent of the Trademark owner. Convention and largely restricted in Europe. It continues to be detected in aquatic 18 environments, with only limited studies into the on-going sources. This paper explores PFOS 19 emissions discharged by the general population into a small catchment comprising of two 20 rivers in the UK. A sampling campaign was undertaken to improve our understanding of 21 population-derived PFOS sources from sewage treatment plants (STPs) and in rivers. A 22 corresponding modelling exercise allowed an emission estimate of 13 µg/day/per capita to be 23 derived for the Aire and Calder rivers. PFOS emission was linked to STP discharges, and 24 thereby population density, by using a correlation with the artificial sweetener sucralose, a 25 conservative chemical marker for waste water (R 2 = 0.69). The model was able to accurately 26 estimate the spatial trends of PFOS in the rivers, while predicted concentrations were within a 27 factor of three based on per capita emission values taken from the literature. Measured PFOS 28 concentrations in rivers suggested that emissions from STPs are partially dependent on 29 treatment type, where plants with secondary or tertiary treatment such as activated sludge 30 processes emit less PFOS, possibly due to increased partitioning and retention. With 31 refinements based on the type of treatment at each STP, predictions were further improved. 32 2 The total PFOS mass discharged annually via rivers from the UK has been estimated to be 33 between 215 and 310 kg, based on the per capita emissions range derived in this study. 34
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Comparing Measured and Modelled PFOS Concentrations in a UK
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